The transmission/reception of data in water is performed by mainly using acoustics, and it is proposed that visible light is used for realizing communication of larger capacity data more quickly (for example, refer to PTL 1).
In PTL 1, there is disclosed a visible light communication system in which observation data is transmitted and received to an underwater mobile body which moves underwater from an observation instrument installed in water by optical space transmission using visible light. In PTL 2, a visible light communication cat ion system transmitting and receiving audio data between divers existing underwater by optical space transmission using visible light is disclosed.